The effects of exercise training on the lungs and cardiovascular function of animals exposed to diesel exhaust particles and gases.

Air pollution has been identified as one of the main environmental risks to health. Since exercise training seems to act as an anti-inflammatory modulator, our hypothesis is that exercise training prevents damage to respiratory and cardiovascular function caused by diesel exhaust particle (DEP) exposure. This study aimed to evaluate whether aerobic exercise training prior to DEP exposure prevents inflammatory processes in the pulmonary and cardiovascular systems. Therefore, BALB/C male mice were or were not submitted to a 10-week exercise training protocol (5×/week, 1 h/d), and after four weeks, they were exposed to DEP in a chamber with 24 µg/m3 PM2.5 or filtered air. Heart rate variability, lung mechanics and bronchoalveolar lavage fluid, cytokines and polymorphonuclear cells in the lung parenchyma were evaluated. Exposure to DEPs reduced heart rate variability and the elastance of the respiratory system and increased the number of cells in bronchoalveolar lavage fluid, as well as macrophages, neutrophils and lymphocytes, the density of polymorphonuclear cells and the proportion of collagen fibres in the lung parenchyma. Additionally, DEP-exposed animals showed increased expression of IL-23 and IL-12p40 (proinflammatory cytokines) and inducible nitric oxide synthase. Exercise training avoided the increases in all these inflammatory parameters, except the elastance of the respiratory system, the amount of collagen fibres and the expression of inducible nitric oxide synthase. Additionally, trained animals showed increased expression of the anti-inflammatory cytokine IL-1ra. Although our data showed a reduction in proinflammatory markers and an increase in markers of the anti-inflammatory pathway, these changes were not sufficient to prevent damage to the lung and cardiovascular function induced by DEPs. Based on these data, we propose that aerobic exercise training prevents the lung inflammatory process induced by DEPs, although it was not sufficient to avoid chronic damage, such as a loss of lung function or cardiovascular events.

Exercise reverses OVA-induced inhibition of glucocorticoid receptor and increases anti-inflammatory cytokines in asthma.

The purpose of this study was to determine the effect of aerobic exercise training (AT) on the expression of glucocorticoid receptors (GR) and anti-inflammatory cytokines in an asthma model. BALB/c mice were divided into groups control (CT; nonsensitized/nontrained), aerobic training (AT; nonsensitized/trained), ovalbumin (OVA; sensitized/not trained), and OVA+AT (sensitized/trained). OVA groups received OVA by inhalation, and the AT groups completed 1, 3, or 7 days of exercise (60 min/session). Expression of GR, IL-4, IL-5, IL-10, IL-1ra, NF-κB, TGF-ß, VEGF, ICAM-1, VCAM-1; eosinophils counting; and airway remodeling (AR) features [airway smooth muscle (ASM) and epithelial thickness and collagen fiber deposition] were quantified. OVA sensitization induced a decrease in the expression of GR and increases in the eosinophil, IL-4, IL-5, NF-κB, TGF-ß, VEGF, ICAM-1, VCAM-1, and AR features (P < 0.05). After 3 days, AT reversed the OVA-induced reduction in the expression of GR, and subsequently induced increases in the expression of IL-10 and IL-1ra (seventh day). In contrast, the eosinophil migration, the expression of NF-κB, IL-4, IL-5, TGF-ß, RANTES, VEGF, ICAM-1, VCAM-1, and the AR features (P < 0.05) were reduced. AT increases the expression of GR and anti-inflammatory cytokines (IL-10 and IL-1ra) and reduces the expression of inflammatory mediators and airway inflammation in an animal model of asthma.

Airway remodeling is reversed by aerobic training in a murine model of chronic asthma.

The aim of this study was to investigate if the aerobic training (AT) reverses airway remodeling (AR) in an asthma model. BALB/c were divided into four groups: control (unsensitized and untrained); ovalbumin (OVA: sensitized and untrained); AT (unsensitized and trained) and OVA + AT. Allergic inflammation was induced with intraperitoneal and OVA inhalation. AT (low intensity; 5×/week; 60 min/session) was performed at 7, 15, and 30 days. Leukocyte counting in the bronchoalveolar lavage fluid; the expression of IL-5, eotaxin, RANTES, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1); AR features (airway smooth muscle, epithelium thickness, collagen and elastic fibers, mucus production); and AR inducers (transforming growing factor-beta, osteopontin, vascular endothelial growth factor). OVA induced an increase in leukocyte airway migration and increased AR features (P < 0.05). After 7 days, AT reversed the OVA-induced eosinophil and macrophage airway migration, the expression of IL-5, eotaxin, RANTES, ICAM-1, VCAM-1, and all AR inducers. However, total reversion of the AR features and inducers and airway inflammation occurred only after 15 days of AT compared with the OVA groups (P < 0.05) and the effects were maintained until the 30th day. AT reverses AR after 15 days and this effect is preceded by the inhibition of leukocyte migration and occurs simultaneously with the reduction in the expression of inflammatory mediators and AR inducers.

A comparative study of extracellular matrix remodeling in two murine models of emphysema.

A single instillation of porcine pancreatic elastase (PPE) results in significant airspace enlargement on the 28th day after instillation, whereas cigarette smoke (CS) exposure requires 6 months to produce mild emphysema in rodents. Considering that there are differences in the pathogenesis of parenchymal destruction in these different experimental models, it is likely that there may be different patterns of extracellular matrix (ECM) remodeling. To evaluate ECM remodeling, C57BL/6 mice were submitted to either a nasal drop of PPE (PPE 28 Days) or exposed for 6 months to cigarette smoke (CS 6 months). Control groups received either an intranasal instillation of saline solution (Saline 28 Days) or remained without any smoke inhalation for six months (Control 6 months). We measured the mean linear intercept and the volume proportion of collagen type I, collagen type III, elastin and fibrillin. We used emission-scanning confocal microscopy to verify the fiber distribution. Both models induced increased mean linear intercept in relation to the respective controls, being larger in the elastase model in relation to the CS model. In the CS model, emphysema was associated with an increase in the volume proportion of fibrillin, whereas in the PPE model there was an increase in the parenchymal elastin content. In both models, there was an increase in collagen type III, which was higher in the CS-exposed mice. We concluded that ECM remodeling is different in the two most used experimental models of emphysema.